In the world of multi-ingredients products, in particular cleaning products, the formulator is faced with a series of challenges including incompatibility among different ingredients, the need of delivering ingredients in pre-determined amounts, the sequential release of different ingredients, etc.
Some of these challenges have been tackled before, however, the design of a product overcoming the above issues usually involve cumbersome processes and complex products. For example, the literature presents various solutions to the problem of ingredient incompatibility and sequential release. U.S. Pat. No. 5,133,892 discloses a multilayer detergent tablet containing an outer layer, a barrier layer and an inner layer. The tablet sequentially releases ingredients contained in the outer layer and ingredients contained in the inner layer. The time interval between the release of the outer layer ingredients and the release of the inner layer ingredients is controlled by the particular choice of an ingredient for the barrier layer and the relative thicknesses of the inner layer, the barrier layer and the outer layer. The tablet is able to separate in time the dissolution of incompatible ingredients such as enzymes and chlorine bleach. The tablet also provides sequential release of a dishwashing composition and a rinse aid composition such that cleaning is accomplished prior to the release of the rinse aid. This multilayer tablet not only requires a complex manufacturing process but also the use of a high number of non-active ingredients, ie, ingredients that do not contribute to the cleaning process such as those used in the barrier layer.
Cleaning products in the form of water-soluble pouches, sachets and capsules are becoming more widely available. Ingredient separation can also be achieved by means of multi-compartment pouches such as those described in WO 02/42,401. '401 describes dual compartment pouches comprising different compositions in different compartments.
The modification of water-soluble films to improve their handling properties is known in the literature. EP 479,404 relates to a composite packaging film comprising a continuous water-soluble base film carrying on one or both surfaces a discontinuous, at least partially non-particulate layer of a second plastics material which is less water-soluble than the base film material, for example, nitrocellulose. The composite film is produced by applying the second material from a non-aqueous solution onto the base film to form a discontinuous pattern. The discontinuous layer may be applied by printing.
WO 01/23,460 relates to a water-soluble film having a water-insoluble material present on a surface thereof, wherein the water-insoluble material is used in an amount of 0.1 to 80% by weight of the film and is in the form of particles having an average particle diameter of less than 500 μm or fibres having a length of 10 μm to 6 mm. The film has high storage stability and good feel to the touch. The water-insoluble material may be fixed to the water-soluble film by a binder. The water-insoluble material and the binder are delivered to the water-soluble material dispersed or dissolved in an organic solvent.
WO 03/031637 discloses a method of manufacturing reversible flexible substrates with actives embedded/entrapped therein. The amount of actives that can be embedded/entrapped into the film is limited by the film dimensions. It seems that high levels of active cannot be achieved with '637's method.
EP 1,275,368 relates to a perfume containing composition suitable for adding a low level of perfume to water-soluble films. The composition requires a silicone-base surfactant.
There remains the need of a method to load high level of actives onto water-soluble films without altering the properties of the film.